Method to make an elastomeric polyolefin skin

ABSTRACT

The present invention relates to method to make a spray skin from an aqueous polyolefin dispersion composition comprising a an olefin block copolymer, a dispersing agent, preferably an ethylene acrylic acid, and water, wherein said aqueous dispersion preferably has a pH less than 12 and is derived from the melt blending. The method comprises the steps of spraying the aqueous polyolefin dispersion onto a heated mold forming the skin and then allowing it to dry.

FIELD OF THE INVENTION

The present invention relates to a method for producing a flexibleelastomeric polyolefin skin wherein an aqueous polyolefin dispersion issprayed onto a mold surface and the polyolefin dispersion is allowed todry to produce the skin layer. The aqueous polyolefin dispersion isderived from the melt blending of thermoplastic polymer, a dispersingagent, and water, wherein said aqueous dispersion preferably has a pHless than 12.

BACKGROUND OF THE INVENTION

There are several methods to make skins for plastic articles, forexample skins on an automotive interior article, such as an instrumentpanel, door panel, console, glove compartment cover, etc. Positivethermoforming, negative thermoforming, shush molding, and sprayed arefour major processes used to make skins for such interior articles.

Textured skin sheets for internal automotive furnishings, such asinstrument panels, door trim and so on, were made principally of softpolyvinyl chloride resin (PVC). In recent years, however, olefinicthermoplastic elastomers have been used. Textured skins of olefinicthermoplastic elastomers may be produced by a number of techniquesincluding positive and negative vacuum forming. Positive vacuum formingis carried out using a non-grained forming mold having perforations forevacuating the interface between the mold surface and the textured skinsheet (texture is formed on the outer face of an extruded sheet byembossing prior to vacuum forming) inside face by placing the texture orgrain sheet on the mold with its textured outer face being exposed tothe exterior and pressing the sheet onto the mold face by evacuating thespace beneath the sheet. Therefore, the patterns of the textured outerface of the textured sheet may be apt to undergo deformation during theprocess of forming. In particular, a textured skin made of an olefinicthermoplastic elastomer may suffer from such deformation of the patternupon a vacuum forming, especially upon positive vacuum forming, moreeasily as compared with that made of soft PVC, resulting in an inferiorability for retaining the texture.

Slush molding and spray processes offer the most design freedom withsome process advantages. In the slush molding technique, a free-flowing,powdered polymer is charged to an open top container or box, i.e., aslush box. A heated mold in the form of the article or object to bemolded is clamped on top of the slush box, and the container rotated ina manner such that the free-flowing polymer powder contacts the hot moldwhere the powder melts and flows over the mold. The container is thenreturned to its original position, the mold removed from the container,and the article removed from the mold. This technique can realizecomplex shapes with sharp edges and excellent grain retention.

Until recently, polyvinyl chloride (PVC) resins were the material ofchoice for interior skins, and they are ideally suited for slushmolding. However, PVC formulations suffer from migration andvolatilization of the plasticizers over time, and this leads both tophysical property changes in the PVC as it ages and to fogging of thecar window glass. PVC also suffers from being heavier than alternativematerials (an important consideration in the current design ofautomobiles with the emphasis on lighter materials to reduce the overallweight of the vehicle and thus increase its gas efficiency).Additionally, the hardness, storage modulus, and brittleness of PVCincreases as the ambient temperature decreases, and thus at lowtemperatures, e.g., about −40° C., the instrument panel skin upon airbagdeployment could splinter.

Alternatives to PVC include thermoplastic polyurethanes (TPU),thermoplastic polyolefins (TPO), and polyolefin elastomers (POE) whichcan be engineered to have the necessary flow characteristics requiredfor slush molding. TPU has good scratch and mar properties and betterlow temperature properties than PVC, but aromatic based TPU has poorultraviolet (UV) light resistance. Aliphatic isocyanates can be used toprepare TPU having good UV light resistance but at a significant costpenalty.

Blends of polypropylene (PP) and a polyolefinic rubber, referred to asthermoplastic polyolefin (TPO), is yet another alternative. TPO possesbetter ductility than PVC. Moreover, it retains its ductility over timesince it does not contain any low molecular weight plasticizers, as doesPVC. TPO performs better in comparison to PVC in interior automotiveapplications. TPO is less expensive as compared to TPU.

Recently, new polyolefin elastomer (POE) resins have been shown to havegood scratch and mar resistance, excellent low temperature properties,adequate hardness (e.g., Shore A hardness) while demonstrating goodpowder flow characteristics and the ability to be pulverized at ambienttemperature, see US Publication No. 2012/0172534.

Polyurethanes have been the resins of choice for spray processes.Suitable polyurethane reaction mixtures for spraying flexibleelastomeric polyurethane skins are disclosed in U.S. Pat. Nos. 5,656,677and 8,709,324. A polyurethane reaction mixture is sprayed onto a moldsurface and allowed to cure to produce the skin layer. The polyurethanereaction mixture is composed of components comprising at least anisocyanate component (either aliphatic or aromatic), isocyanate-reactivecomponents and a catalyst component, the isocyanate component beingcomposed of at least one isocyanate having at least two NCO— groupswhich are not directly attached to an aromatic group. However,polyurethanes based on aliphatic isocyanates are not light-stablepolyurethanes and may require an in-mold coating and/or a post-paintingstep to avoid discoloration of the skin.

Instead of producing the polyurethane skins from aliphatic polyurethaneformulations, it is also possible to produce them from aromaticpolyurethane formulations, i.e. from polyurethane formulations theisocyanate component of which comprises an aromatic instead of analiphatic polyisocyanate. As disclosed for example in U.S. Pat. No.6,544,449 such aromatic polyurethane formulations have importantadvantages over aliphatic polyurethane formulations. Aromaticpolyurethane formulations produce polyurethane elastomers having moreparticularly better physical properties such as higher tensile and tearstrengths and better elongation and “cold flex” capability. A drawbackof aromatic polyurethane elastomers is however that they become lessstable after prolonged exposure to light resulting in physical propertydeteriation. For both aliphatic and aromatic solvent based polyurethaneformulations, volatile organic compounds (VOCs) are released and scrapis not recyclable. Further, polyurethane spray process equipmentrequires complex mixing capabilities to mix the polyurethane reactionmixture as well as the need for solvent flushing.

There is a need for a process to make skins for automotive interiorparts that offers reduced complexity while using a more environmentallyfriendly resin composition which is recyclable and generates minimal tono VOCs.

SUMMARY OF THE INVENTION

The present invention is a process for making a spray skin comprisingthe steps of: (i) spraying an aqueous polyolefin dispersion onto aheated mold, preferably equal to or greater than 50° C., forming asprayed skin having a first surface and a second surface, and (ii)allowing the sprayed skin to dry, wherein the aqueous polyolefindispersion is derived from the melt blending of (A) a polyolefincomposition comprising an olefin block coploymer in the presence of (B)at least one dispersing agent and (C) water, wherein said aqueousdispersion preferably has a pH less than 12.

In one embodiment of the process of the present invention describedherein above, the polyolefin composition comprising the olefin blockcopolymer further comprises one or more of a random olefin copolymer, apolyethylene, a propylene, a propylene, ethylene, α-olefin, anon-conjugated dienes based copolymers, an ethylene-vinyl acetate, anethylene-vinyl alcohol, a chlorinated polyethylene, an alcoholfunctionalized polyolefin, an amine functional polyolefin, or a silanegrafted polyolefin.

In one embodiment of the process of the present invention describedherein above, the dispersing agent is ethylene acrylic acid (EAA),ethylene-methacrylic acid (EMA), ethylene ethyl acrylate (EEA)copolymer, ethylene methyl methacrylate (EMMA), or ethylene butylacrylate (EBA).

In one embodiment of the process of the present invention describedherein above, the polyolefin composition comprises one or more of a dye,a pigment, an organic filler, an inorganic filler, a plasticizer, astabilizer, a surfactant, an anti-static agent, a tackifier, an oilextender, a crosslinking agent, a chemical blowing agent, ananti-microbial agent, a thickening agent, or an age resister.

In another embodiment of the process of the present invention describedherein above, the process further comprises the step of (iii) providinga foam backing to the second surface of the spray skin.

In one embodiment of the process of the present invention describedherein above, the process further comprises the step of (iv) applying apaint layer to the first surface of the spray skin.

In yet a further embodiment the process of the present inventiondescribed herein above, the process further comprises the step (iii) ofapplying a paint layer to the first surface of the spray skin and thestep of (iv) providing a foam backing to the second surface of the sprayskin.

In yet a further embodiment the process of the present inventiondescribed herein above the aqueous polyolefin dispersion is blended withan aqueous colorant

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic representation of a typical melt-extrusionapparatus used to prepare the aqueous pour point depressant dispersioncompositions of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The process of the present invention is a process for making a sprayskin from an aqueous polyolefin dispersion, specifically an aqueouspolyolefin dispersion derived from the melt blending of a polyolefincomposition comprising an olefin block copolymer, a dispersing agent,and water, wherein said aqueous dispersion preferably has a pH less than12.

The olefin block copolymers (OBC) used in the practice of this inventionare well known, for example see U.S. Pat. Nos. 8,455,576; 7,579,408;7,355,089; 7,524,911; 7,514,517; 7,582,716; and 7,504,347; all of whichare incorporated in their entirety herein by reference.

“Olefin block copolymer”, “olefin block interpolymer”, “multi-blockinterpolymer”, “segmented interpolymer” and like terms refer to apolymer comprising two or more chemically distinct regions or segments(referred to as “blocks”) preferably joined in a linear manner, that is,a polymer comprising chemically differentiated units which are joinedend-to-end with respect to polymerized olefinic, preferable ethylenic,functionality, rather than in pendent or grafted fashion. In a preferredembodiment, the blocks differ in the amount or type of incorporatedcomonomer, density, amount of crystallinity, crystallite sizeattributable to a polymer of such composition, type or degree oftacticity (isotactic or syndiotactic), regio-regularity orregio-irregularity, amount of branching (including long chain branchingor hyper-branching), homogeneity or any other chemical or physicalproperty. Compared to block interpolymers of the prior art, includinginterpolymers produced by sequential monomer addition, fluxionalcatalysts, or anionic polymerization techniques, the multi-blockinterpolymers used in the practice of this invention are characterizedby unique distributions of both polymer polydispersity (PDI or Mw/Mn orMWD), block length distribution, and/or block number distribution, due,in a preferred embodiment, to the effect of the shuttling agent(s) incombination with multiple catalysts used in their preparation. Morespecifically, when produced in a continuous process, the polymersdesirably possess PDI from 1.7 to 3.5, preferably from 1.8 to 3, morepreferably from 1.8 to 2.5, and most preferably from 1.8 to 2.2. Whenproduced in a batch or semi-batch process, the polymers desirablypossess PDI from 1.0 to 3.5, preferably from 1.3 to 3, more preferablyfrom 1.4 to 2.5, and most preferably from 1.4 to 2.

The term “ethylene multi-block interpolymer” means a multi-blockinterpolymer comprising ethylene and one or more interpolymerizablecomonomers, in which ethylene comprises a plurality of the polymerizedmonomer units of at least one block or segment in the polymer,preferably at least 90, more preferably at least 95 and most preferablyat least 98, mole percent of the block. Based on total polymer weight,the ethylene multi-block interpolymers used in the practice of thepresent invention preferably have an ethylene content from 25 to 97,more preferably from 40 to 96, even more preferably from 55 to 95 andmost preferably from 65 to 85, percent.

Because the respective distinguishable segments or blocks formed fromtwo of more monomers are joined into single polymer chains, the polymercannot be completely fractionated using standard selective extractiontechniques. For example, polymers containing regions that are relativelycrystalline (high density segments) and regions that are relativelyamorphous (lower density segments) cannot be selectively extracted orfractionated using differing solvents. In a preferred embodiment thequantity of extractable polymer using either a dialkyl ether or analkane-solvent is less than 10, preferably less than 7, more preferablyless than 5 and most preferably less than 2, percent of the totalpolymer weight.

In addition, the multi-block interpolymers used in the practice of theinvention desirably possess a PDI fitting a Schutz-Flory distributionrather than a Poisson distribution. The use of the polymerizationprocess described in WO 2005/090427 and U.S. Ser. No. 11/376,835 resultsin a product having both a polydisperse block distribution as well as apolydisperse distribution of block sizes. This results in the formationof polymer products having improved and distinguishable physicalproperties. The theoretical benefits of a polydisperse blockdistribution have been previously modeled and discussed in Potemkin,Physical Review E (1998) 57 (6), pp. 6902-6912, and Dobrynin, J. Chem.Phvs. (1997) 107 (21), pp 9234-9238.

In a further embodiment, the polymers of the invention, especially thosemade in a continuous, solution polymerization reactor, possess a mostprobable distribution of block lengths. In one embodiment of thisinvention, the ethylene multi-block interpolymers are defined as having:

-   -   (A) Mw/Mn from about 1.7 to about 3.5, at least one melting        point, Tm, in degrees Celsius, and a density, d, in grams/cubic        centimeter, where in the numerical values of Tm and d correspond        to the relationship        Tm>−2002.9+4538.5(d)−2422.2(d)², or    -   (B) Mw/Mn from about 1.7 to about 3.5, and is characterized by a        heat of fusion, ΔH in J/g, and a delta quantity, ΔT, in degrees        Celsius defined as the temperature difference between the        tallest DSC peak and the tallest CRYSTAF peak, wherein the        numerical values of ΔT and ΔH have the following relationships:        ΔT>−0.1299(ΔH)+62.81 for ΔH greater than zero and up to 130 J/g        ΔT>48 C for ΔH greater than 130 J/g    -   wherein the CRYSTAF peak is determined using at least 5 percent        of the cumulative polymer, and if less than 5 percent of the        polymer has an identifiable CRYSTAF peak, then the CRYSTAF        temperature is 30 C; or    -   (C) Elastic recovery, Re, in percent at 300 percent strain and 1        cycle measured with a compression-molded film of the        ethylene/α-olefin interpolymer, and has a density, d, in        grams/cubic centimeter, wherein the numerical values of Re and d        satisfy the following relationship when ethylene/α-olefin        interpolymer is substantially free of crosslinked phase:        Re>1481−1629(d); or    -   (D) Has a molecular weight fraction which elutes between 40 C        and 130 C when fractionated using TREF, characterized in that        the fraction has a molar comonomer content of at least 5 percent        higher than that of a comparable random ethylene interpolymer        fraction eluting between the same temperatures, wherein said        comparable random ethylene interpolymer has the same        comonomer(s) and has a melt index, density and molar comonomer        content (based on the whole polymer) within 10 percent of that        of the ethylene/α-olefin interpolymer; or (E) Has a storage        modulus at 25 C, G′(25 C), and a storage modulus at 100 C,        G′(100 C), wherein the ratio of G′(25 C) to G′(100 C) is in the        range of about 1:1 to about 9:1.    -   The ethylene/α-olefin interpolymer may also have:    -   (F) Molecular fraction which elutes between 40 C and 130 C when        fractionated using TREF, characterized in that the fraction has        a block index of at least 0.5 and up to about 1 and a molecular        weight distribution, Mw/Mn, greater than about 1.3; or    -   (G) Average block index greater than zero and up to about 1.0        and a molecular weight distribution, Mw/Mn greater than about        1.3.

Suitable monomers for use in preparing the ethylene multi-blockinterpolymers used in the practice of this present invention includeethylene and one or more addition polymerizable monomers other thanethylene. Examples of suitable comonomers include straight-chain orbranched α-olefins of 3 to 30, preferably 3 to 20, carbon atoms, such aspropylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene,4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene,1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene; cyclo-olefinsof 3 to 30, preferably 3 to 20, carbon atoms, such as cyclopentene,cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene, and2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene; di-and polyolefins, such as butadiene, isoprene, 4-methyl-1,3-pentadiene,1,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, 1,4-hexadiene,1,3-hexadiene, 1,3-octadiene, 1,4-octadiene, 1,5-octadiene,1,6-octadiene, 1,7-octadiene, ethylidenenorbornene, vinyl norbornene,dicyclopentadiene, 7-methyl-1,6-octadiene,4-ethylidene-8-methyl-1,7-nonadiene, and 5,9-dimethyl-1,4,8-decatriene;and 3-phenylpropene, 4-phenylpropene, 1,2-difluoroethylene,tetrafluoroethylene, and 3,3,3-trifluoro-1-propene.

Other ethylene multi-block interpolymers that can be used in thepractice of this invention are elastomeric interpolymers of ethylene, aC₃₋₂₀ α-olefin, especially propylene, and, optionally, one or more dienemonomers. Preferred α-olefins for use in this embodiment of the presentinvention are designated by the formula CH₂═CHR*, where R* is a linearor branched alkyl group of from 1 to 12 carbon atoms. Examples ofsuitable α-olefins include, but are not limited to, propylene,isobutylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and1-octene. One particularly preferred α-olefin is propylene. Thepropylene based polymers are generally referred to in the art as EP orEPDM polymers. Suitable dienes for use in preparing such polymers,especially multi-block EPDM type-polymers include conjugated ornon-conjugated, straight or branched chain-, cyclic- or polycyclicdienes containing from 4 to 20 carbon atoms. Preferred dienes include1,4-pentadiene, 1,4-hexadiene, 5-ethylidene-2-norbornene,dicyclopentadiene, cyclohexadiene, and 5-butylidene-2-norbornene. Oneparticularly preferred diene is 5-ethylidene-2-norbornene.

Because the diene containing polymers contain alternating segments orblocks containing greater or lesser quantities of the diene (includingnone) and α-olefin (including none), the total quantity of diene andα-olefin may be reduced without loss of subsequent polymer properties.That is, because the diene and α-olefin monomers are preferentiallyincorporated into one type of block of the polymer rather than uniformlyor randomly throughout the polymer, they are more efficiently utilizedand subsequently the crosslink density of the polymer can be bettercontrolled. Such crosslinkable elastomers and the cured products haveadvantaged properties, including higher tensile strength and betterelastic recovery.

The ethylene multi-block interpolymers useful in the practice of thisinvention have a density of less than 0.90, preferably less than 0.89,more preferably less than 0.885, even more preferably less than 0.88 andeven more preferably less than 0.875, g/cc. The ethylene multi-blockinterpolymers typically have a density greater than 0.85, and morepreferably greater than 0.86, g/cc. Density is measured by the procedureof ASTM D-792. Low density ethylene multi-block interpolymers aregenerally characterized as amorphous, flexible and having good opticalproperties, e.g., high transmission of visible and UV-light and lowhaze.

The ethylene multi-block interpolymers useful in the practice of thisinvention typically have a melt flow rate (MFR) of 1-10 grams pr 10minutes (g/10 min) as measured by ASTM D1238 (190° C./2.16 kg).

The ethylene multi-block interpolymers useful in the practice of thisinvention have a 2% secant modulus of less than about 150, preferablyless than about 140, more preferably less than about 120 and even morepreferably less than about 100, mPa as measured by the procedure of ASTMD-882-02. The ethylene multi-block interpolymers typically have a 2%secant modulus of greater than zero, but the lower the modulus, thebetter the interpolymer is adapted for use in this invention. The secantmodulus is the slope of a line from the origin of a stress-straindiagram and intersecting the curve at a point of interest, and it isused to describe the stiffness of a material in the inelastic region ofthe diagram. Low modulus ethylene multi-block interpolymers areparticularly well adapted for use in this invention because they providestability under stress, e.g., less prone to crack upon stress orshrinkage. The ethylene multi-block interpolymers useful in the practiceof this invention typically have a melting point of less than about 125.The melting point is measured by the differential scanning calorimetry(DSC) method described in WO 2005/090427 (US2006/0199930). Ethylenemulti-block interpolymers with a low melting point often exhibitdesirable flexibility and thermoplasticity properties useful in thefabrication of the wire and cable sheathings of this invention.

The polyolefin composition comprising an OBC may further comprise one ormore of a random olefin copolymer, a polyethylene, a propylene, apropylene, ethylene, alpha-olefin, a non-conjugated dienes basedcopolymers (EPDM), an ethylene-vinyl acetate, an ethylene-vinyl alcohol,a chlorinated polyethylene, an alcohol functionalized polyolefin, anamine functional polyolefin, or a silane grafted polyolefin.

The aqueous polyolefin dispersion of the present invention uses adispersing agent (or stabilizing agent) to promote the formation of astable dispersion or emulsion. In selected embodiments, the stabilizingagent may be a surfactant, a polymer (different from the OBC polymerdetailed above), or mixtures thereof. In certain embodiments, thepolymer may be a polar polymer, having a polar group as either acomonomer or grafted monomer. Examples of suitable polar polyolefin areethylene-vinyl acetate, ethylene-vinyl alcohol, chlorinatedpolyethylene, alcohol or amine functional polyolefin, silane graftedpolyolefin. In preferred embodiments, the stabilizing agent comprisesone or more polar polyolefins, having a polar group as either acomonomer or grafted monomer. For example, the dispersing agent mayinclude an ethylene/alpha-beta unsaturated carboxylic acid copolymer. Insome embodiments, the ethylene/alpha-beta unsaturated carboxylic acidcopolymer may include an ethylene-acid copolymer, such as anethylene-acrylic acid copolymer or an ethylene methacrylic acidcopolymer.

Typical polymers include ethylene-acrylic acid (EAA) andethylene-methacrylic acid copolymers, such as those available under thetrademarks PRIMACOR™ (trademark of The Dow Chemical Company), NUCREL™(trademark of E.I. DuPont de Nemours), and ESCOR™ (trademark ofExxonMobil) and described in U.S. Pat. Nos. 4,599,392; 4,988,781; and5,938,437, each of which is incorporated herein by reference in itsentirety. Other polymers include ethylene-methacrylic acid (EMA),ethylene ethyl acrylate (EEA) copolymer, ethylene methyl methacrylate(EMMA), and ethylene butyl acrylate (EBA). Other ethylene-carboxylicacid copolymer may also be used. Those having ordinary skill in the artwill recognize that a number of other useful polymers may also be used.

Other surfactants that may be used include long chain fatty acids orfatty acid salts having from 12 to 60 carbon atoms. In otherembodiments, the long chain fatty acid or fatty acid salt may have from12 to 40 carbon atoms.

If the polar group of the polymer is acidic or basic in nature, thestabilizing polymer may be partially or fully neutralized with aneutralizing agent to form the corresponding salt. In certainembodiments, neutralization of the stabilizing agent, such as a longchain fatty acid or EAA, may be from 25% to 200% on a molar basis; from50% to 110% on a molar basis in other embodiments. For example, for EAA,the neutralizing agent is a base, such as ammonium hydroxide orpotassium hydroxide, for example. Other neutralizing agents may includelithium hydroxide or sodium hydroxide, for example. Those havingordinary skill in the art will appreciate that the selection of anappropriate neutralizing agent depends on the specific compositionformulated, and that such a choice is within the knowledge of those ofordinary skill in the art.

Additional surfactants that may be useful in the practice of the presentinvention include cationic surfactants, anionic surfactants,zwitterionic, or non-ionic surfactants. Examples of anionic surfactantsinclude sulfonates, carboxylates, and phosphates. Examples of cationicsurfactants include quaternary amines Examples of non-ionic surfactantsinclude block copolymers containing ethylene oxide and siliconesurfactants. Surfactants useful in the practice of the present inventionmay be either external surfactants or internal surfactants. Externalsurfactants are surfactants that do not become chemically reacted intothe polymer during dispersion preparation. Examples of externalsurfactants useful herein include salts of dodecyl benzene sulfonic acidand lauryl sulfonic acid salt. Internal surfactants are surfactants thatdo become chemically reacted into the polymer during dispersionpreparation. An example of an internal surfactant useful herein includes2,2-dimethylol propionic acid and its salts.

In particular embodiments, the dispersing agent or stabilizing agent maybe used in an amount ranging from greater than zero to about 60% byweight based on the amount of base polymer (or base polymer mixture)used. For example, long chain fatty acids or salts thereof may be usedin an amount ranging from 0.5% to 10% by weight based on the amount ofbase polymer. In other embodiments, ethylene-acrylic acid orethylene-methacrylic acid copolymers may be used in an amount from 0.5%to 60% by weight based on polymer. In yet other embodiments, sulfonicacid salts may be used in an amount from 0.5% to 10% by weight based onthe amount of base polymer.

While any method may be used, one convenient way to prepare the aqueouspour point dispersion compositions described herein is by melt-kneading.Any melt-kneading means known in the art may be used. In someembodiments a kneader, a Banbury mixer, single-screw extruder, or amulti-screw extruder is used. The melt-kneading may be conducted underthe conditions which are typically used for melt-kneading the OBC resin.A process for producing the dispersions in accordance with the presentinvention is not particularly limited. One preferred process, forexample, is a process comprising melt-kneading the OBC and EAA, and anyother additives according to U.S. Pat. Nos. 5,756,659; 7,763,676; and7,935,755, all of which are incorporated herein by reference in theirentirety. A preferred melt-kneading machine is, for example, a multiscrew extruder having two or more screws, to which a kneading block canbe added at any position of the screws. If desired, it is allowable thatthe extruder is provided with a first material-supplying inlet and asecond material-supplying inlet, and further third and forthmaterial-supplying inlets in this order from the upper stream to thedownstream along the flow direction of a material to be kneaded.Further, if desired, a vacuum vent may be added at an optional positionof the extruder. In some embodiments, the pour point dispersioncomprising the thermoplastic polymer, dispersing agent, and any otheradditives is first diluted to contain about 1 to about 3 percent byweight of water and then subsequently further diluted to comprisegreater than 25 percent by weight of water. In some embodiments, thefurther dilution provides a dispersion with at least about 30 percent byweight of water. The aqueous dispersion obtained by the melt kneadingmay be further supplemented with a glycol, preferably ethylene glycol.The aqueous pour point depressant dispersions described hereinabove maybe used as prepared or diluted further with additional water and/orglycol.

FIG. 1 schematically illustrates an extrusion apparatus which can beused in the process of the present invention. An extruder 20, preferablya twin screw extruder, is coupled to a back pressure regulator, meltpump, or gear pump, 30. Preferably, the apparatus further comprises abase reservoir 40 and an initial water reservoir 50, each of whichincludes a pump (not shown). Desired amounts of base and initial waterare provided from the base reservoir 40 and the initial water reservoir50, respectively. Any suitable pump may be used, but in some embodimentsa pump that provides a flow of about 150 cc/min at a pressure of 240 barmay be used to provide the base and the initial water to the extruder20. In other embodiments, a liquid injection pump provides a flow of 300cc/min at 200 bar or 600 cc/min at 133 bar. In some embodiments the baseand initial water are preheated in a preheater.

The OBC, in the form of pellets, powder, or flakes, is fed from thefeeder 80 to an inlet 90 of the extruder 20 where the resin is melted orcompounded. In some embodiments, the EAA dispersing agent and/orstabilizing agent is added to the resin through an opening along withthe resin and in other embodiments, the dispersing agent and/orstabilizing agent is provided separately to the twin screw extruder 20.The resin melt is then delivered from the mix and convey zone to anemulsification zone of the extruder where the initial amount of waterand base from the reservoirs 40 and 50 is added through inlet 55. Insome embodiments, dispersing agent may be added additionally orexclusively to the water stream. In some embodiments, the emulsifiedmixture is further diluted with additional water and/or glycol and/orstabilizing agent via inlet 95 from reservoir 60 in a dilution andcooling zone of the extruder 20. Typically, the dispersion is diluted toat least 30 weight percent water in the cooling zone. In addition, thediluted mixture may be diluted any number of times until the desireddilution level is achieved.

In one embodiment of the method to make the aqueous polyolefindispersions of the present invention, step a, all of the OBC, thedispersing agent EAA; and water are combined to form an aqueousdispersion of OBC in one step.

In a another embodiment of the method to make the aqueous polyolefindispersions of the present invention, some or all of the water and/orstabilizing agent is not added into the twin screw extruder 20 butrather, step b, to a stream containing the dispersed polymer after ithas exited from the extruder. In other words, step b does not occur inthe extruder in which the aqueous dispersion of OBC is produced. In thismanner, steam pressure build-up in the extruder 20 is minimized.

In a preferred embodiment, a basic substance or aqueous solution,dispersion or slurry thereof is added to the dispersion at any point ofthe process, preferably to the extruder. Typically the basic substanceis added as an aqueous solution. But in some embodiments, it is added inother convenient forms, such as pellets or granules. In someembodiments, the basic substance and water are added through separateinlets of the extruder. Examples of the basic substance which may beused for the neutralization or the saponification in the melt kneadingprocess include alkaline metals and alkaline earth metals such assodium, potassium, calcium, strontium, barium; inorganic amines such ashydroxylamine or hydrazine; organic amines such as methylamine,ethylamine, ethanolamine, cyclohexylamine, tetramethylammoniumhydroxide; oxide, hydroxide, and hydride of alkaline metals and alkalineearth metals such as sodium oxide, sodium peroxide, potassium oxide,potassium peroxide, calcium oxide, strontium oxide, barium oxide, sodiumhydroxide, potassium hydroxide, calcium hydroxide, strontium hydroxide,barium hydroxide, sodium hydride, potassium hydride, calcium hydride;and weak acid salts of alkaline metals and alkaline earth metals such assodium carbonate, potassium carbonate, sodium hydrogencarbonate,potassium hydrogencarbonate, calcium hydrogencarbonate, sodium acetate,potassium acetate, calcium acetate; or ammonium hydroxide. In particularembodiments, the basic substance is a hydroxide of an alkaline metal ora hydroxide of an alkali metal. In some embodiments, the basic substanceis selected from potassium hydroxide, sodium hydroxide and combinationsthereof.

The OBC polymer of the aqueous polyolefin dispersion of the presentinvention has an advantageous particle size distribution. In particularembodiments, the dispersed OBC polymer has a particle size distributiondefined as volume average particle diameter (Dv) divided by numberaverage particle diameter (Dn) of equal to or less than 2.5, preferablyequal to or less than 2.0. In other embodiments, the dispersions have aparticle size distribution of less than or equal to 1.9, 1.7, or 1.5.

A preferred volume average particle size is equal to or less than 2micron (μm), preferably equal to or less than 1.5 μm, preferably equalto or less than 1.2 μm, and more preferably equal to or less than 1 μm.In other embodiments, the average particle size ranges from 0.05 μm to 1μm. In still other embodiments, the average particle size of thedispersion ranges from 0.5 μm to 1.2 μm, preferably 0.5 μm to 1 μm. Forparticles that are not spherical the diameter of the particle is theaverage of the long and short axes of the particle. Particle sizes canbe measured on a Coulter LS230 light-scattering particle size analyzeror other suitable device.

The dispersions of the present invention have a pH equal to or greaterthan 5, preferably equal to or greater than 8, and more preferably equalto or greater than 10. The dispersions of the present invention have apH equal to or less than 13.5, preferably equal to or less than 13, andmore preferably equal to or less than 12.

The aqueous polyolefin dispersion of the present invention maybe appliedthrough a nozzle of any suitable spray equipment, for example a spraygun. The dispersion is sprayed onto the surface of a mold. The surfaceof the mold may be smooth, i.e., no texture, or preferably the surfaceof the mold may be textured with any desirable texture. The spray skinpreferably has an average thickness of at least 0.5 mm, preferably of atleast 0.75 mm and more preferably of at least 1 mm After the aqueouspolyolefin dispersion of the present invention has been sprayed onto themold surface it is allowed to dry. Depending on the desired thickness ofthe final skin, more than one spray application may be performed, insuch an embodiment, a first layer is sprayed and allowed to dry, asecond layer is sprayed and allowed to dray, and a third layer issprayed and allowed to dry, etc. until the desired number of layers/skinthickness is achieved. The thickness and texture is selected to providea unique skin touch and high quality feeling. The spray skin of thepresent invention has a first surface and a second surface.

In one embodiment, the mold is heated, preferably to temperature equalto or greater than 50° C., more preferably equal to or greater than 65°C., and more preferably equal to or greater than 80° C. Preferably, themold is heated, to temperature equal to or less than 110 C, morepreferably equal to or less than 100° C., and more preferably equal toor less than 90° C. The aqueous polyolefin dispersion of the presentinvention may comprise one or more of a dye, a pigment, an organicfiller, an inorganic filler (including clay, talc, calcium carbonate,titanium dioxide, glass fiber, carbon fibers, nano-sized particles), aplasticizer, a stabilizer (such as, but not limited to antioxidants, UVstabilizers, fire retardants, and the like), a surfactant, ananti-static agent, a tackifier, an oil extender (including paraffinic ornapthelenic oils), a crosslinking agent (such as sulfur, peroxide,phenolic, silane or azide based compounds), a chemical blowing agent, ananti-microbial agent, a thickening agent, or an age resister.

In one embodiment of the process of the present invention the aqueouspolyolefin dispersion is blended with an aqueous colorant. Preferably,the aqueous colorant comprises one or more of a dye, a pigment, anorganic filler, an inorganic filler (including clay, talc, calciumcarbonate, titanium dioxide, glass fiber, carbon fibers, nano-sizedparticles), a plasticizer, a stabilizer (such as, but not liited toantioxidants, UV stabilizers, fire retardants, and the like), asurfactant, an anti-static agent, a tackifier, an oil extender(including paraffinic or napthelenic oils), a crosslinking agent (suchas sulfur, peroxide, phenolic, silane or azide based compounds), achemical blowing agent, an anti-microbial agent, a thickening agent, oran age resister.

In one embodiment of the process of the present invention the aqueouspolyolefin dispersion is blended with other aqueous of dispersions (forexample an aqueous acrylic dispersion or an aqueous polyurethanedispersion) to create a hybrid dispersion that may improve haptics,gloss, and abrasion performance

In one embodiment of the process of the present invention the aqueouspolyolefin dispersion is charged. This may enable greater transferefficiency to a grounded mold and/or improved skin quality.

In one embodiment of the process of the present invention one or bothsurfaces of the skin of the present invention may further be laminatedor bonded to another structure such as a molded plastic article by anysuitable means, such as back injection molding, with adhesives, or asupholstery replacing leather or PVC leather-look. In this embodiment,the process of the present invention comprises the step of laminatingthe skin to another structure.

In one embodiment of the process of the present invention one or bothsurface of the spray skin may be painted providing a layer of paint onone or both surface of the spray skin. The paint may be applied in moldprior to forming the spray skin or out of the mold after the spray skinis formed. In this embodiment, the process of the present inventioncomprises the step of applying a layer of paint to the spray skin,either in-mold or after the skin is formed. The paint layer may beadhered directly to the spray skin or may have an adhesive layer inbetween.

In one embodiment of the process of the present invention one or bothsurface of the spray skin may comprise a foam backing, preferably apolyurethane foam backing. In this embodiment, the process of thepresent invention comprises the step of applying a foam backing to oneor both surface of the spray skin, preferably by foaming the backingonto the spray skin in a mold. The foam backing may be adhered directlyto the spray skin or may have an adhesive layer in between.

In one embodiment of the process of the present invention a paint layeris applied to the first surface of the spray skin and a foam backing,preferably a polyurethane foam backing is applied to the second surfaceof the spray skin.

The foregoing may be better understood by the following Examples, whichare presented for purposes of illustration and are not intended to limitthe scope of this invention.

EXAMPLES

The following aqueous polyolefin dispersions comprise a polyolefinpolymer, a dispersing agent, water, and are neutralized with KOH. Thecompositions of the Examples 1 to 5 are given in Table 1. In Table 1:

“OBC-1” is an ethylene octene block copolymer having 10.4% octene,having a density of 0.887 g/cm³, a 5 g/10 min melt flow rate (MFR)determined at 190° C. under a load of 2.16 Kg, a melting temperature of123° C., a heat of fusion of 70 J/g and a Shore A hardness of 83available as INFUSE™ D9530 from The Dow Chemical Company;

“OBC-2” is an ethylene octene block copolymer having 15.3% octene,having a density of 0.866 g/cm³, a 5 g/10 min MFR (190° C./2.16 Kg), amelting temperature of 123° C., a heat of fusion of 31 J/g and a Shore Ahardness of 60 available as INFUSE 9507 from The Dow Chemical Company;

“SLEP” is a substantially linear ethylene-octene copolymer elastomerwith a 5 g/10 min MFR (190° C./2.16 Kg) and a density of 0.868 g/cm³available as ENGAGE™ 8200 from The Dow Chemical Company;

“EAA” is an ethylene acrylic acid copolymer having 20% acrylic acid witha density of 0.958 g/cm³, a 300 g/10 min MFR (190° C./2.16 Kg), and amelting temperature of 78° C. available as PRIMACOR™ 5980i from The DowChemical Company; and

“UNICID™ 350” is a C₂₆ carboxylic acid having an acid value of 115 KOH/gavailable from Baker Petrolite.

In the following Examples a polyolefin resin is dispersed using themethod described in U.S. Pat. No. 7,763,676, which is herebyincorporated by reference in its entirety, using a dispersing agent andwater as the solvent. The extruder based mechanical dispersion processimparts high shear on a polymer melt/water mixture to facilitate a watercontinuous system with small polymer particles in the presence ofsurface active agents that reduce the surface tension between thepolymer melt and water. A high solids content water continuousdispersion is formed in the emulsification zone of the extruder alsoknown as high internal phase emulsion (HIPE) zone, which is thengradually diluted to the desired solids concentration, as the HIPEprogresses from the emulsification zone to the first and second dilutionzones.

The polyolefin polymer is fed into the feed throat of the extruder bymeans of a loss-in weight feeder. The dispersion agent is added with thepolyolefin polymer. The extruder and its elements are made of NitridedCarbon Steel. The extruder screw elements are chosen to performdifferent unit operations as the ingredients pass down the length of thescrew. There is first a mixing and conveying zone, next anemulsification zone, and finally a dilution and cooling zone. Steampressure at the feed end is contained by placing kneading blocks andblister elements between the melt mixing zone and was contained andcontrolled by using a Back-Pressure Regulator. ISCO dual-syringe pumpsmetered the Initial Water, Base, and Dilution flows to their respectiveinjection ports. The polyolefin, dispersing agent, and water are meltkneaded in the twin screw extruder at a screw RPM of 1150 andneutralized with KOH. Process parameters and product characteristics aresummarized in Table 1. In Table 1, the mean particle size of thedispersed polymer phase is measured by a Coulter LS230 particle analyzerconsisted of an average volume diameter in microns. Viscosity isdetermined according to Brookfield Viscometer. Solids are determined bymoisture analyzer. Filterable residue is determined by filtrationthrough a 70 mesh (200 um) Too much residue can have a negative impacton the ability to spray via a nozzle gun

Spray skins are made for each of Example 1 to 5 by spraying thedispersion with a hand held pneumatic spray gun on 5 inch by 5 inchgrained tool that is pre-heated to 80° C. in a convection oven. After acouple of layers of applied skin, the tool is placed back in the oven toremove the moisture. The process is repeated till a 1 mm skin isproduced. This is achieved by weighing the tool and spraying the tooltill ˜10 g of skin is deposited.

The skins made with Example 5 (using a non-EAA dispersing agent) did notmake good skin. The skin cracked on drying, is brittle, and the filmforming process is not effective.

The haptics of the skins produced with EAA (Examples 1 to 4) are verygood and is improved with the amount of EAA. The skins feel soft andpliable and the grain replication is good.

Heat Resistance.

Small sections are cut from the skins for Examples 1 to 4 and are agedin an oven at 100° C. for 4 hrs. The skins for Examples 2 to 4maintained their integrity and demonstrated good retention of thetexture. Example 1 melted (the base elastomer has a melting point of 65°C.).

Scratch and Abrasion Resistance.

Examples 2 and 3 are scratched using a GM scratch device set at 15N. Novisible scratch results.

Adhesion to Polyurethane Foam Backing.

Examples 2 and 3 are backed with a typical polyurethane foam system. TheA-side is PAPI 94 isocyanate and the B-side is detailed in Table 2. Theindex of the foam is 100 and resulting density is 9 pounds per cubicfoot.

The foaming is carried out using a Graco machine using a 20 inch by 20inch by 0.5 inch mold. The skin is placed in the mold, the mold isclosed, and the polyurethane is foamed onto it. The samples are peeledmanually and examined for the amount of cohesive failure. Example 2showed 50% cohesion, Example 3 to 5 showed 100% cohesion.

Polyurethane Paint Adhesion.

The same mold and molding machine used herein above are used todetermine paint adhesion to a foam-backed skin. The mold temperature isset at 75° C. The sequence of molding is: (1) Apply the paint to themold surface, the paint is Red Spot 558W, a 1 component PU waterborneflexible paint used in applications requiring flexible usage like seatsand arm rests. (2) Cure the paint layer (˜250 um thick). This wasfollowed by (3) manual spraying of Example 3 to make a skinapproximately 0.5 mm in thickness. The dispersion is applied slowly inlayers allowing for sufficient drying time. A hand-held paint is used tospray the dispersion. The spray dried dispersion made a good qualityskin that stuck well to the PU paint. (4) the polyurethane foam to athickness of about 12.5 mm. The mold insert is removed to allow betterheat transfer; enabling improved drying of the dispersions. The demoldtime is 4 minutes. Paint and foam adhesion to the skin is excellent.

The A-side is SPECFLEX NE344 isocyanate and the B-side is detailed inTable 3.

TABLE 1 Example 1* Example 2 Example 3 Example 4 Example 5* COMPOSITIONPolyolefin, % SELP, 60 OBC-1, 77.5 OBC-1, 60 OBC-1, 30 OBC-2, 93 andOBC-2, 40 Dispersing agent, % EAA, 40 EAA, 22.5 EAA, 40 EAA, 40 UNICID,7 Base KOH KOH KOH KOH KOH Degree of Neutralization, % 84.9 85.1 84.984.9 84.9 Target solids, wt % 42 41 42 42 42 PROCESS PARAMETER Extruderpressure, psi 325 520 428 442 390 Extruder outlet temperature, ° C. 9998 98 98 97 Dispersion temperature, ° C. 26 35 35 34 33 Extruder amps 7983 84 76 74 PRODUCT CHARACTERISTICS Mean particle size, micron 1.34 1.451.37 1.25 0.97 pH 10.07 10.38 10.09 10.11 10.24 Viscosity @ 20 RPM, cP288 116 314 26 290 Actual solids, wt % 40.57 39.03 40.24 40.33 38.87Filterable residue, ppm 26 42 19 67 23 *not an example of the presentinvention

TABLE 2 B-Side Components Parts Polyols VORANOL ™ CP 6001 70.50SPECFLEX ™ NC 630 10.00 Copolymer Polyol SPECFLEX NC 701 10.00Crosslinkers TEOA-99 0.85 DEOA Pure 0.15 Chain Extender 1,4 BDO 0.50Catalysts DABCO ™ BL-19/A-99 JEFFCAT ™ ZF-10 0.30 TOYOCAT ™ RX-20 0.90POLYCAT ™ 15 0.20 Cell Opener VORANOL 4053 1.00 Adhesion PromoterDIEXTER ™ G 156T-63 2.50 Colorant REACTINT ™ Black 2151 0.40 BlowingAgent Water 2.70 Total 100.00 VORANOL CP 6001 is a polyol available fromThe Dow Chemical Company. SPECFLEX NC 630 is a polyol available from TheDow Chemical Company. SPECFLEX NC 701 is a cpp polyol available from TheDow Chemical Company. TEOA-99 is triethanolamine catalyst available fromSierra Chemical Company. DEOA Pure is Diethanolamine available from AirProducts. 1,4 BDO is butanediol available from Evonik. Dabco BL-19 isblowing catalyst available from Air Products. JEFFCAT ZF-10 is blowingcatalyst available from Huntsman Corporation(N,N,N′-trimethyl-N′-hydroxyethyl bisaminoethylether). TOYOCAT RX-20 isan amine catalyst available from Tosoh. POLYCAT 15 is a low emissionreactive amine catalyst available from Air Products. VORNAL 4053 is ahigh functionality EO-rich cell opener available from The Dow ChemicalCompany. DIEXTER G 156T-63 is saturated polyester available from Coim.REACTINT Black 2151 is a black concentrate available from MillikenChemical.

TABLE 3 B-Side Component Parts polyols VORANOL 4701 33.91 SPECFLEX NC630 25.67 Copolymer Polyol SPECFLEX NC 701 35.51 Cell Opener VORANOL CP1421 1.52 Crosslinker DEOA LF 0.96 Surfactant TEGOSTAB B 8729 LF2 0.30Catalysts DABCO NE210 0.30 POLYCAT 15 0.71 JEFFCAT DPA 0.61 Water 0.51Total 100 VORNAL 4701 is a polyol available from The Dow ChemicalCompany. SPECFLEX NE 344 an isocyanate available from The Dow ChemicalCompany. VORANOL CP 1421 is a polyol, used as a cell opener availablefrom The Dow Chemical Company. DEOA LF is diethanolamine available fromAir Products. TEGOSTAB B 8729 LF2 is silicone surfactant available fromEvonik. DABCO NE210 is low emission amine catalyst available from AirProducts. JEFFCAT DPA is low emission amine catalyst available fromHuntsman.

What is claimed is:
 1. A process for making a spray skin comprising thesteps of: (i) spraying an aqueous polyolefin dispersion onto a heatedmold forming a sprayed skin having a first surface and a second surface,and (ii) allowing the sprayed skin to dry, wherein the aqueouspolyolefin dispersion is derived from the melt blending of (A) apolyolefin composition comprising an olefin block copolymer in thepresence of (B) at least one dispersing agent which is a polar polymerand (C) water and wherein the aqueous polyolefin dispersion consistsessentially of the olefin block copolymer, the dispersing agent, water,and optionally one or more of dye, a pigment, an organic filler, aninorganic filler, a plasticizer, a stabilizer, a surfactant, ananti-static agent, a tackifier, an oil extender, a chemical blowingagent, an anti-microbial agent, a thickening agent, an age resister, anaqueous acrylic dispersion, or an aqueous polyurethane dispersion. 2.The process of claim 1 wherein (A) the polyolefin composition comprisingthe olefin block copolymer further comprises one or more of a randomolefin copolymer, a polyethylene, a propylene, a propylene, ethylene,α-olefin, a non-conjugated dienes based copolymers, an ethylene-vinylacetate, an ethylene-vinyl alcohol, a chlorinated polyethylene, analcohol functionalized polyolefin, an amine functional polyolefin, or asilane grafted polyolefin.
 3. The process of claim 1 wherein (B) thedispersing agent comprises a polymer selected from the group consistingof ethylene acrylic acid (EAA), ethylene-methacrylic acid (EMA),ethylene ethyl acrylate (EEA), ethylene methyl methacrylate (EMMA), orethylene butyl acrylate (EBA).
 4. The process of claim 1 wherein theaqueous polyolefin dispersion is derived from the melt blending of (A)an olefin block copolymer in the presence of (b) an ethylene acrylicacid as a dispersing agent and (C) water.
 5. The process of claim 1wherein the polyolefin composition comprises one or more of a dye, apigment, an organic filler, an inorganic filler, a plasticizer, astabilizer, a surfactant, an anti-static agent, a tackifier, an oilextender, a crosslinking agent, a chemical blowing agent, ananti-microbial agent, a thickening agent, or an age resister.
 6. Theprocess of claim 1 wherein the mold is heated to equal to or greaterthan 50° C.
 7. The process of claim 1 further comprising the step of(iii) applying a paint layer to the first surface of the spray skin. 8.The process of claim 1 further comprising the step of (iv) providing afoam backing to the second surface of the spray skin.
 9. The process ofclaim 1 further comprising the step of (iii) applying a paint layer tothe first surface of the spray skin and the step of (iv) providing afoam backing to the second surface of the spray skin.
 10. The process ofclaim 1 wherein the aqueous polyolefin dispersion is blended with anaqueous colorant.
 11. The process of claim 1 further comprising bondingthe skin to another structure.
 12. The process of claim 11 wherein thebonding comprises laminating.
 13. The process of claim 7 which forms anautomotive interior article.
 14. The process of claim 8 which forms anautomotive interior article.
 15. The process of claim 11 which forms anautomotive interior article.
 16. The process of claim 1 wherein theaqueous polyolefin dispersion consists of the olefin block copolymer,the dispersing agent, water, and optionally one or more of dye, apigment, an organic filler, an inorganic filler, a plasticizer, astabilizer, a surfactant, an anti-static agent, a tackifier, an oilextender, a chemical blowing agent, an anti-microbial agent, athickening agent, an age resister, an aqueous acrylic dispersion, or anaqueous polyurethane dispersion.